Project Summary/Abstract Colitis-associated cancer (CAC) refers to the pathological transition from inflammatory bowel disease (IBD) to colorectal cancer (CRC). Burgeoning evidence suggests that the abnormal intercellular crosstalk between the gut microbiome and inflammatory host cells is highly associated with the development of CAC. Thus, mapping the microbial signature and epithelial plasticity in response to the host-microbiome intercellular crosstalk is critical to mechanistically decipher the role of gut microbiome on the CAC pathogenicity. However, current animal models neither reflect the heterogeneous genetic variants in CAC patients nor quantitatively visualize host- microbiome molecular crosstalk in a spatiotemporal manner. In vitro co-culture models lack the long-term stability to perform a longitudinal host-microbiome study that is necessary to investigate the pathological intercellular crosstalk. Hence, developing a patient-specific CAC model that can quantitatively assess the cellular and molecular signature of host-microbiome crosstalk is a critical unmet need to map the pathological host-gut microbiome crosstalk and unravel their cause vs. consequence in CAC. The long-term goal of the outlined research is to develop transformative and implementable engineered cancer model systems that encompass cancer-microbiome crosstalk. In the F99 phase of this proposed research, a patient-specific CAC-on-a-chip model will be developed by utilizing a cutting-edge human organ-on-a-chip technology. The effects of gut microbiome in the development of CAC will be investigated using this model system. In the K00 phase, single- cell analysis and multi-omics approach will be incorporated into the personalized CAC model for a higher resolution and comprehensive study of the underlying molecular and cellular mechanism of the defined host- microbiome intercellular interactions. By mapping crosstalk between cancer and microbiome, complicated cancer pathobiology will be dissected and manipulated to answer the pressing questions.